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Abstract: SA-PO736

Testican-2 Alleviates Adriamycin-Induced Podocyte Injury by Modulating Vitronectin-Integrin αVβ3 Interaction

Session Information

Category: Glomerular Diseases

  • 1304 Glomerular Diseases: Podocyte Biology

Authors

  • Wen, Donghai, Massachusetts General Hospital, Boston, Massachusetts, United States
  • Rosales, Ivy A., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Colvin, Robert B., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Waikar, Sushrut S., Boston University, Boston, Massachusetts, United States
  • Zhou, Wen, Massachusetts General Hospital, Boston, Massachusetts, United States
  • Pollak, Martin, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Rhee, Eugene P., Massachusetts General Hospital, Boston, Massachusetts, United States
Background

Testican-2 is a podocyte-derived glycoprotein encoded by the gene SPOCK2. Its circulating levels are associated with higher estimated glomerular filtration rate (eGFR) and slower rate of subsequent eGFR decline in two large racially diverse cohorts. The biological function of testican-2 in podocytes is unknown.

Methods

Immortalized cultured human podocytes were treated with adriamycin with or without testican-2, and then actin cytoskeleton disruption was examined to assess podocyte injury. BALB/c male mice were treated with adriamycin together with placebo (eGFP) or Spock2 adenovirus. Three weeks later, urine spot albumin/creatinine and glomerulosclerosis were examined. To further investigate the underlying mechanisms of testican-2 on podocyte function, immunoprecipitation-mass spectrometry (IP-MS) was utilized to examine the potential binding proteins of testican-2 in the extra-cellular matrix (ECM) of cultured human podocytes. Bio-Layer Interferometry (BLI) was utilized to further confirm their interactions. Finally, glomerular testican-2 expression levels of human kidney biopsy samples from patients with primary focal glomerulosclerosis (FSGS) and normal control subjects were examined by immunofluorescence (IF).

Results

Testican-2 significantly reduced adriamycin-induced podocyte actin cytoskeleton disruption. Treatment of Spock2 adenovirus also improved adriamycin-induced albuminuria and glomerulosclerosis as compared to eGFP adenovirus. IP-MS identified vitronectin as one of the binding partners for testican-2, which was further verified by BLI. In addition, BLI showed that testican-2 inhibits the interaction between vitronectin and integrin αVβ3, which is an anchored protein that has been shown to play an important role in podocyte injury. Administration of testican-2 also reduced adriamycin-induced activation of integrin αVβ3 in cultured human podocytes and mouse glomeruli as examined by IF. Finally, glomerular testican-2 expression was reduced in patients with FSGS as compared to normal control subjects.

Conclusion

Testican-2 alleviates adriamycin-induced podocyte injury, likely through modulating vitronectin-integrin αVβ3 interaction

Funding

  • NIDDK Support